Hi, Copying files to vfat FS on an NVDIMM device hits BUG_ON(!PageLocked(page)) in try_to_free_buffers(). It happens on 4.13-rc1, and happens on older kernels as well. A simple reproducer is shown below. It is 100% reproducible on my setup (8GB of regular memory and 16GB of NVDIMM). It usually hits in the 3rd or 4th file copy and does not repeat with the while-loop. Interestingly, it hits only when an NVDIMM device is set as raw or memory mode. It does not hit with sector mode. == DEV=pmem0 set -x mkfs.vfat /dev/$DEV mount /dev/$DEV /mnt/$DEV dd if=/dev/zero of=/mnt/$DEV/1Gfile bs=1M count=1024 while true; do cp /mnt/$DEV/1Gfile /mnt/$DEV/file-1 cp /mnt/$DEV/1Gfile /mnt/$DEV/file-2 cp /mnt/$DEV/1Gfile /mnt/$DEV/file-3 cp /mnt/$DEV/1Gfile /mnt/$DEV/file-4 cp /mnt/$DEV/1Gfile /mnt/$DEV/file-5 cp /mnt/$DEV/1Gfile /mnt/$DEV/file-6 cp /mnt/$DEV/1Gfile /mnt/$DEV/file-7 cp /mnt/$DEV/1Gfile /mnt/$DEV/file-8 cp /mnt/$DEV/1Gfile /mnt/$DEV/file-9 cp /mnt/$DEV/1Gfile /mnt/$DEV/file-10 done == kernel BUG at fs/buffer.c:3305! invalid opcode: 0000 [#1] SMP : Workqueue: writeback wb_workfn (flush-259:0) task: ffff8d02595b8000 task.stack: ffffa22242400000 RIP: 0010:try_to_free_buffers+0xd2/0xe0 RSP: 0018:ffffa22242403830 EFLAGS: 00010246 RAX: 00afffc000001028 RBX: 0000000000000008 RCX: ffff8d012dcf19c0 RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffc468e3b52b80 RBP: ffffa22242403858 R08: 0000000000000000 R09: 000000000002067c R10: ffff8d027ffe6000 R11: 0000000000000000 R12: 0000000000000000 R13: ffff8d022fccdbe0 R14: ffffc468e3b52b80 R15: ffffa22242403ad0 FS: 0000000000000000(0000) GS:ffff8d027fd40000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f9d2bb80b70 CR3: 000000084fe09000 CR4: 00000000007406e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 PKRU: 55555554 Call Trace: clean_buffers+0x5d/0x70 __mpage_writepage+0x567/0x760 ? page_mkclean+0x6a/0xb0 write_cache_pages+0x205/0x580 ? clean_buffers+0x70/0x70 ? fat_add_cluster+0x80/0x80 [fat] mpage_writepages+0x7c/0x100 ? fat_add_cluster+0x80/0x80 [fat] ? __set_page_dirty+0x9b/0xc0 ? fprop_fraction_percpu+0x2f/0x80 fat_writepages+0x15/0x20 [fat] ? fat_writepages+0x15/0x20 [fat] do_writepages+0x25/0x80 __writeback_single_inode+0x45/0x350 writeback_sb_inodes+0x25e/0x610 __writeback_inodes_wb+0x92/0xc0 wb_writeback+0x29b/0x340 wb_workfn+0x195/0x3d0 ? wb_workfn+0x195/0x3d0 process_one_work+0x193/0x3d0 worker_thread+0x4e/0x3d0 kthread+0x114/0x150 ? process_one_work+0x3d0/0x3d0 ? kthread_park+0x60/0x60 ? kthread_park+0x60/0x60 ret_from_fork+0x25/0x30 : RIP: try_to_free_buffers+0xd2/0xe0 RSP: ffffa22242403830 Thanks, -Toshi
